LEXINGTON, Ky. – Aided by four yearlings that sold for $300,000 or more, Keeneland’s September yearling sale in Lexington maintained some of its earlier momentum Saturday as Book 3 kicked off. The sixth of 13 sessions posted more gains as compared to the first session for Book 3 last year.

Saturday’s session, the first in Book 3, sold 280 yearlings for a collective price of $20,613,500, up 24 percent from 2010’s seventh session, the Book 3 opener after a longer Book 2; the 2011 sale trimmed its Book 2 catalog by one day. Last year’s Book 3 opener sold 284 yearlings for $16,636,500.

This year’s session average rose 26 percent, from $58,579 last year to $73,620, and the $51,000 median gained 2 percent from last season’s $50,000.

Buybacks remained almost level with last year. In 2010, the figure was 23.6 percent, and that edged down ever so slightly to 23.5 percent Saturday.

Cumulatively, the 2011 vendue’s first six days have sold 1,033 yearlings for $165,830,000, up 5 percent from last year’s aggregate. Median and average also remain on a stronger pace this year, with the $110,000 cumulative median up 38 percent and the $160,532 average 24 percent ahead of last year’s figure.

Barbara Banke’s Stonestreet Stables, which earlier this week sold a $1.2 million Street Cry-Forest Music colt to racing partner George Bolton, bought Saturday’s session-topper, a $425,000 Elusive Quality colt out of the Saint Ballado mare Pinafores Pride. The Ontario-bred colt is a half-brother to Canadian graded stakes winner Southdale. Anderson Farms consigned the bay on behalf of Rod Ferguson.

Mike Pegram bought a $400,000 daughter of first-crop sire War Pass and unraced stakes-producer Avenging Tomisue, by Belong to Me. The dark bay or brown filly is a half-sister to stakes winner Striking Tomisue. The family is that of champion sprinter Aldebaran and Grade 1 winner Good Journey.

Lane’s End was the consignor.

Pegram also paid $300,000 for a Hill ‘n’ Dale agency-consigned Indian Charlie colt out of Indigene, a Deputy Minister mare from the family of champion juvenile filly Althea. The bay colt, a late April foal, is a half-brother to stakes-placed Pretty Katherine.

Mike Repole, represented by agent J. J. Crupi, also picked up an expensive colt when he paid $320,000 for a Pulpit son of Exploding Star from Claiborne Farm’s agency. The dark bay or brown colt is a May 11 foal and is a half-brother to last year’s Grade 2-placed Eden Star.

Nineteen horses at the session sold for $200,000 or more.

Saturday’s session resumed selling after a dark day Friday and followed a remarkably strong first week for the 13-day auction.

The sale’s first week, including the first two select sessions, put the auction ahead of last year’s figures. The first five sessions, which ended Thursday, sold 753 yearlings for $145,216,500, a 22 percent increase over the equivalent sessions in 2010. The $192,851 average price was up 18 percent, and the $150,000 median was 36 percent higher than at the same time last year.

Meanwhile, buybacks fell from 32 percent to 27 percent.

Through Thursday, the auction had sold six yearlings for $1 million or more, including the $1.4 million sale-leader. That was an A.P. Indy colt out of Malka that the Hill ‘n’ Dale Sales agency sold to a partnership led by John Amerman and Robert “Shel” Evans.

The September sale was to continue through Sept. 24 with sessions daily from 10 a.m. in the Keeneland sale pavilion.